Mercury relay of impulse type



Jan. 22, 1957 LENNlNG 778,990

MERCURY RELAY OF IMPULSE TYPE Filed Jan. 31, 1955' INVENTOR. AA VAR[f/V/V/A/G B BY Qua/$1,;

MERCURY RELAY OF IMPULSE TYPE Alvar Lenning, Stockholm, Sweden, assignorto Ab Inreco, Stockholm, Sweden, a corporation of Sweden ApplicationJanuary 31, 1955, Serial No. 485,175

Claims priority, application Sweden February 4, 1954 4 Claims. (Cl.200-112) An impulse relay in that sense in which the term is being usedin this specification may be defined as a relay which is to be actuatedby electric current surges or impulses having a relatively shortduration. The action of such a relay consists in alternatingly makingand breaking a main circuit in response to such impulses which mayoriginate e. g. from pressing a push button.

The patent literature comprises a number of specifications pertaining toimpulse relays of the mercury type, as well as to mechanical ones. Thebest dependability as to insensitivity to wear and to occasional shortcircuits appears to be obtainable with mercury type relays, particularlywhen small size relays are being considered. When the magnet coilwattage is of the order of around 2 watts, as is usual with impulserelays, it is difficult to maintain large enough contact gaps if therelay is of a purely mechanical type.

In mercury relays, on the other hand, one or both of the followingshortcomings usually prevail: (l) the relay function is not suriicientlypositive, i. e. the device will once in a while fail to respond properlyto a current impulse; (2) the switching action is-by the nature of therelay designnot immediately completed upon closing the current; i. e.the auxiliary current has to be interrupted as well to bring about thefinal phase of the switching action. The aim of the present invention isto overcome both of these objections.

The invention will presently be described in conjunction with theaccompanying drawing in which Fig. l represents a sectional elevation ofthe new relay. Fig. 2 is an end view taken from the left of theembodiment shown in Fig. 1. Figs. 3, 4, and 5 are cross sections throughthe glass body of the relay in Figs. 1 and 2, showing the interior partsin various phases of operation. Fig. 6 illustrates in perspective themagnet core and pole shoe system employed; Figs. 7 and 8 are perspectiveviews of the two movable parts inside the glass body: a soft steelarmature member, and a contact carrying nonmagnetic swing body,respectively. The same reference numbers are used throughout.

in Fig. 1 reference number 1 is a cylindrical glass bulb having (in itsproper operational position) an essentially horizontal axis or shaft. Itcontains a mercury filling which is distributed between two pools, 2 and3, by means of the glass ridge 4. A magnet coil 5 having a soft steelcore is disposed on top of the glass cylinder. The bentin core legs aretriangular in shape and are to serve as pole shoes (6 and 7); thecomplete core is more clearly illustrated in Fig. 6. At the bottom ofthe glass cylinder 1 a curved steel plate is provided for the purpose ofabsorbing stray magnetic fields. This will slightly reduce the coilwattage required for operating the relay.

The glass cylinder is equipped with two main electrodes, 9 and 1%), ofwhich 9 is in contact with mercury pool 2, and it) with mercury pool 3.The electrode 9 also serves as an axis for carrying the movable membersinside the glass cylinder. Said members are a soft steel armature Illand a non-magnetic swing body 12 of which the latter nited States Patent0 2,778,900 Patented Jan. 22, 1957 is preferably made of steatite. Inone of its ends the swing body is equipped with a protruding lug 13which cooperates with the armature 11. In Fig. 7 is shown that thearmature body in one of its ends is shaped like a triangular window 14which gives a certain latitude of relative motion (back lash) betweenthe armature 11 and the lug 13 (compare Fig. 8). In Figs. 1, 2, and 8 isshown that the swing body also carries a double bent contact member 15the purpose of which is to connect electrically the mercury pools 2 and3.

The relay works as follows. Fig. 3 may be said to represent the initialposition where both of the rotatable members, 11 and 12, are at restagainst the top of the glass ridge 4. The contact member 15 in saidposition connects the two mercury pools, i. e. keeps the main currentclosed. Now when the magnet coil 5 is energized by means of an auxiliarycurrent the armature 11 will rotate turn on its axis, owing to themagnetic attraction from the triangular pole shoes 6 and 7, and willcome to a temporary rest in the position illustrated by Fig. 4. In thecourse of its motion the left radial frame member of the armature window14 will have hit the lug 13 of the swing body, thus transferring part ofits momentum to the swing body; this, as a consequence will be thrownpast its upper dead center and thereafter comes to rest against theopposite radial frame member of the window 14 as shown in Fig. 4. Insaid position the contact member 15 is lifted away from the mercurypools 2 and 3, i. e. the main current is interrupted.

When the magnet coil is tie-energized the swing body, owing to itsgravity, will carry the armature 11 over towards the right whereafterboth members come to rest as shown in Fig. 5. The main current thusremains interrupted.

At the next current impulse through the magnet coil 5 the armaturemember 11 first rotates turn in an anti-clockwise direction; in thecourse of its motion it throws the swing body over towards the left, andinto the position given in Fig. 2. Already at this instance the contactmember 15 has re-established the electrical connection between themercury pools, i. e. the main current is being closed immediately as theimpulse producing push button (not shown) is being pressed. Whendeenergizing the magnet coil both of the members 11 and 12 drop backinto their original positions according to Fig. 3.

It should be apparent that the proper functioning of the relay dependson the feature that the center of gravity of the swing body issufliciently offset from a vertical plane through the axis of rotationto be able to carry over the armature from its top dead center positiontowards its own side. It also depends on properly choosing the angularopening of the armature window 14. This opening angle should be smallenough to allow the swing body to receive its impetus before thearmature has reached its top dead center position, and at the same timesulficiently large to permit an angular motion of the swing body beyondits top dead center position allowing contact between member 15 and themercury pools at the phase of operation shown in Fig. 2. To make theentire device as effective as possible in regard to wattage of operationa. certain optimum relation between the inertias of the two members 11and 12 are obviously required. The elastic properties of the two membersshould here also be taken into account. The optimum dimensions are mosteasily determined ex erimentally. it is believed that the relativedimensions shown in the various figures will comparatively well coincidewith said optimum.

Within the scope of the invention several modifications are possible.The armature may e. g. be provided with a lug protrusion, and the swingbody with the frame to cooperate with the lug. Both of the rotatablemembers may I 1. An :electromagnetically operated impulse: relay com-rprising, in combination, a-horizontallydisposed cylindrical glassbulb, apartition dividing the lower wall sectiomof said, bulb into twoportions, a pool of mercury breach of saidgpor-tions, a pair of contactelectrodes extending; through said bulb walls, each ofsaidelectrodesmaking contact with oneof said mercury pools, ashaft'extending longitudinaly througlrsaid bulbon-the centerline-thereof, a v generally U-shaped magnetic armature: memberpivoted byits arms, on said shaft, acontactcarrying member alsqpivoted on saidshaft and a lost motion on ecti n. e en a d' rma rem ntber nd said,contactcarrying. member whereby said armature memberimparts motion toandreceives.motionfrom said contact caItyingmember to cause said contactcarrying member, tomove past deadicenter positionwhile saidarmaturemember is held in dead center position,

2, An impulse relayas claimed in claim 1, wherein-an electromagnethavingv pole pieces extending against the upper: wall of saidcylindrical bulb. causes the armature member to rotate approximately a.quarterturnabont its shaft when said, magnet is energized, said armaturemem ber inthe course of thatmotion imparting to the contact carryingmember a motion; in excess ofaquarter turn. bntless than one-half turn.

3. An impulse, relay as claimed in claim 1, in which, meansare. providedfor mechanically limiting theangnlar motionofthe armature member and ofthe contact carrying member to approximately one-half turn.

4.. An electro-magnetically operated impulserelay comprising, ,in,combination, a horizontally disposed cylindrical glass bulb, atransverse partition dividing thelowerE wall section of said bulb intotwo portions, a pool of mercury in each of said portions, a pair ofcontact electrodes extending through said bulb walls, each ofsaidelectrodes making contact with ,one of said mercury pools, ashaftextending longitudinally throughsaid bulb on the center line thereof, agenerally U-shaped magnetic armature pivoted by its arms on said'shaft,at least one of said arms having an annular slot therein, a contactcarrying memoer also pivoted on said shaft, said member having a lugextending therefrom into the slot of said armature member, said lughavingalesser angular extent than said slot, said armature and contactmembers normally at rest lying on'said partition, magneticpole-.piecesmounted outside saidrbulb substantially at the top thereof,said pole pieces being generally triangular with-the points thereoffacing eachother, said points being substantially at the top ofiisaidcylindrical bulb, and. electrical means comprising a winding on saidpole pieces for magnetically energizing said-pole-pieces to-therebyoperate said U- shaped armature;member-to its uppermost position, saidU-shaped member, by virtue of the lug and slot connection, picking upsaid contact carrying member and causing it to rotate until the lugstrikes the opposite end of the slot, the contacts ofsaid'contactcarrying-member then breakingthe contact with said mercury pool, saidmagnet Winding, upon being deenergized, releasing said armature andpermitting said armature and said contact carrying member to falluntil'th'ey rest on the opposite side of said transverse partition Wall,a subsequent'energization of said imagnet causing the contacts of saidcontact carrying member to be thrown by said armature member intoengagement with said pool of mercury and to be dropped ,upondeenergization of said magnet winding into the original position ofrest.

References. Cited in the file of this patent UNITED STATES PATENTS-2,545,669 Meyer Mar. 20, 1951 2,673,265, Meyer Mar. 23, 1954 2,696,537Andrae et al. Dec. 7, 1954 FOREIGN PATENTS 370,855 France Jan. 5, 1907

